Our overall goal is to clarify the interrelations between steroid hormones and brain functions with morphological, histochemical and biochemical approaches on different functional levels. The specific aim is to obtain quantitative and correlative information of defined cell groups in brain and pituitary on estradiol uptake, estradiol receptors, and estradiol mediated cellular responses. The studies seek to provide information on the relationships between the number of steroid molecules bound, the amount of nuclear receptors, the amount of mRNA for specific cellular products, and the amount of related posttranslational specific products. Secretory products of estrogen target neurons will be identified through colocalization of 3H estradiol and peptide hormones or neurotransmitter related enzymes. The effects of progesterone and sex-related differences in nuclear uptake of 3H estradiol, as well as neuronal binding sites for estrogenic and androgenic metabolites of testosterone will be explored. Techniques developed in our laboratory which will be utilized, include, steroid thaw-mount autoradiography, colocalization of steroid hormones and neuropeptides by combined autoradiography-immunohistochemistry, and computer-assisted quantitative autoradiography. In addition, we will use in situ cDNA hybridization and biochemical assays. In the brain, effects of steroid nuclear uptake on the metabolic activity in different estradiol target regions will be studied with the high resolution 3H-2-deoxyglucose autoradiography. In parallel in vitro studies with pituitary gonadotropes, steroid occupation and effects of sex steroid hormone on gonadotropin, secretion will be studied under different hormonal conditions. The data derived from the experiments will be utilized to develop an integrated model of the interrelations between steroid hormones, especially estradiol, and brain-pituitary functions, particularly for the control of reproduction and fertility.